Paper strengthening resins are sold commercially as aqueous solutions. Commonly such resins are thermosetting, polymeric reaction products of epichlorohydrin and a polyamide derived from a polyalkylene polyamide and certain dicarboxylic acids. U.S. Pat. No. 2,926,154 to Keim describes aqueous solutions of such resins. Typically aqueous solution of such resins contain an amine curing accelerator such as ethylenediamine or diethylenetriamine. Such compositions are disclosed in Espy U.S. Pat. No. 3,442,754. The presence of the accelerator makes it possible to thermally set the resin in a shorter time.
Commercially such aqueous solution usually contain about 10 to 35% by weight resin. Most of the remaining portion of the solution is water.
Such commercial aqueous solutions typically contain epichlilorohydrin, dichloropropanol and chloropropanediol; the latter two compounds are hydrolysis products of epichlorohydrin. These compounds are suspected carcinogens and contribute to environmental pollution during the paper making process.
A variety of references describe the removal of organohalogen compounds from water by use of various adsorbents including ion exchange resins, polymeric adsorbents, silica, alumina, clays, activated carbons, zeolites, etc. See, for example,
K. Dorfner, Ion Exchangers, Properties and Applications. (Ann Arbor Science Publishers Inc., 1972, Ann Arbor); PA1 Ion Exchangers, K. Dorfner, Ed. (Walter de Gruyter, NY, 1991); PA1 Amberlite.RTM. Product and Technical Bulletin, for Amberlite.RTM. IRA-93 ion exchange resin, Rohm and Haas Co., 1981.